September 10, 2010

FOCUS | Sewer and Watermain

Kitchener, Ontario repairing sewer, water lines using trenchless technology

PETER KENTER

correspondent

The City of Kitchener will be giving its sewer and watermains a double dose of attention using trenchless technology to repair sections of both systems. While cured-in-place pipe repair is common for sewer lines, it’s not as widely used for potable water lines where stringent standards determine which products can be used.

The value of the project, centred on the city’s Forest Hill area, is about $2.5 million with federal infrastructure funding of about $1.7 million and provincial infrastructure funding of about $800,000.

“By using trenchless rehabilitation methods, the city will be able to extend the lifespan of this infrastructure by 25 to 50 years at a cost that is less than traditional open-cut reconstruction and replacement,” says Bradley Marin, project manager with Conestoga-Rovers & Associates, the engineering firm chosen to head the project.

“Trenchless rehabilitation techniques offer the city the ability to address more infrastructure in a shorter period of time, at less cost and social disruption than traditional methods. The techniques that will be used on this project include pipe bursting and pipe lining.”

The area targeted by the project is a subdivision — and not a particularly old one at that.

“The infrastructure is 35 to 40 years old, but the challenge for the city has been premature breakage of the watermains,” says Marin. “That’s due to a number of factors, including soil condition, original construction and installation, frost action, water hammer, and movement of the fill from the original project. It’s definitely a wetter area and those underground conditions are still present today. As the soil settles, it puts stress on the longer pieces of pipe and that can cause fatigue and breaks at various locations.”

Marin notes that sewer relining is often less challenging than watermain relining because sewer maintenance holes provide ready access for relining equipment. Access holes must be dug prior to commencement of work on water mains.

“On the sanitary service, it’s also fairly easy to find all of the laterals after the pipe has been lined, since they’re four inches in diameter,” says Marin. “When they send in the CCTV cameras, it’s easy to see where the bulges are that indicate the locations of the laterals, so robot cutters can re-establish sanitary service.”

Water service is less easy to identify.

“When you insert a cork in a 5/8th-inch water line, try to find the service after the liner has been put in,” says Marin. “Historically, that has gone from a near-zero likelihood to a promise of near 80 per cent success. That’s good, because if a new tap is required, that just means more surface interference.”

Fer-Pal Construction Ltd. has been contracted to rehabilitate the water system using the Aqua-Pipe potable water relining system, supplied by Quebec’s Sanexen Environmental Services Inc. Capital Sewer Services Inc. of Hamilton has been retained to provide sewer relining.

The city expects work to be completed by mid-October.

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